Slackchannel2pdf

Fixed

- Shows date & time on thread replies

Added

- Ability to add a logfile

Changed

- Replaced print statements with logger
- No uses `Pathlib` for better cross platform compatibility

Fixed

- 'NoneType' object has no attribute 'decimal_formats'

Fixed

- 'NoneType' object has no attribute 'get_display_name'

Fixed

- Missing timestamp for posts in thread [5](https://github.com/ErikKalkoken/slackchannel2pdf/issues/5)

Changed

- Major refactoring
- Now also uses paging to fetch list of users

Fixed

- Works with general and random but not other channels [4](https://github.com/ErikKalkoken/slackchannel2pdf/issues/4)

Changed

- Improved test coverage

Fixed

- Error 'pretty type' - cant' export slack channel to pdf [3](https://github.com/ErikKalkoken/slackchannel2pdf/issues/3)